Analyses And Design Of Fault-tolerant Multi-three-phase Unit Interior Permanent Magnet Synchronous Machine

Permanent magnet machine drives have seen consistent growth over the last few decades due to their higher efficiency,higher power density,and their implicit validity and reliability for direct-driven applications,among other factors.Despite this,the fact that a permanent magnet machine’s excitation field cannot be switched off at will has historically discouraged engineers from using these drives in safety-critical applications.Historically,much of the research has been conducted on the fault-tolerant permanent magnet machine drives;however,there is an ever-increasing need to propose novel machine design concepts and winding topologies suitable for fault-tolerant applications.The industrial and scientific community has recently been attracted to multi-three-phase machines for fault-tolerant applications.This is mainly because when the phase number increases,the machine design provides significant advantages that can justify using a higher number of phases than the three-phase machines.Similarly,multi-three-phase machines offer several advantages compared to three-phase machines,particularly in terms of fault tolerance and the level of performance that can be achieved following a failure.The primary motivation behind this research is to present the design concept for a multi-three-phase unit motor machine and investigate its magnetic field,vibration,noise,and thermal behavior under normal and particularly under post-fault operating conditions,which have not yet been thoroughly investigated in the literature.This research begins by reviewing related literature and comparing all the faulttolerant machine and drive approaches that have been used in the past.Afterward,various fault-tolerant machine design techniques are presented,revealing that segmenting the machine windings into multiple phases is among the most favorable fault-tolerant machine design techniques.After reviewing the relevant literature for fault-tolerant machine design,the design concept and the proposed design parameters for the fault-tolerant multi-three-phase unit motor machine are presented.This is followed by proposing multiple three-phase sector windings configurations for the analyzed machine.The proposed design guidelines and basic parameters are presented for all the multi-three-phase sector winding designs of the machine prototype.The distribution of magnetic field density,MMF,radial magnetic forces,amplitudes,harmonics,and sub-harmonics(time and space)are examined for the multi-three-phase unit motor machine design for all the analyzed multi-three-phase sector winding designs under normal and fault-tolerant conditions.In the next step,the fault-tolerant multi-three-phase unit motor machine is investigated for its structural,vibration,and noise response analyses for all the proposed multi-three-phase sector winding designs under normal and fault-tolerant conditions.The machine prototype’s vibro-acoustic behavior is studied using a computational method and verified by experimental tests under healthy and fault-tolerant conditions.The design concept and guidelines for the multi-three-phase unit motors machine are also presented,taking the machine prototype with six three-phase units as an example.Each three-phase unit consists of three slots and a pole pair to form a basic unit motor.However,the proposed design concept can be generalized to any repetition of the basic unit motor.An analytical algorithm has been proposed to predict the stator MMF and the corresponding harmonic spectrum for the multi-three-phase unit motor machine under different multi-three-phase sector winding designs.The proposed analytical algorithm can be used to determine the stator MMF harmonics for the healthy and threephase unit motor open-circuit fault cases.Similarly,the generated torque,efficiency,and torque ripples are also investigated for the analyzed multi-three-phase sector winding designs under healthy and fault-tolerant conditions.Lastly,the thermal behaviour of the multi-three-phase unit motor machine is presented for all the analyzed multi-three-phase sector winding designs operated under healthy,partial,and partially overloaded conditions.The machine prototype thermal behaviour is investigated using the coupled magnetic field and thermal analyses technique by applying different multi-three-phase sector winding designs.Moreover,a parametric thermal sensitivity analysis is conducted for the machine design operated under the partially overloaded condition for all the analyzed multi-three-phase-phase sector winding designs,which can prove helpful in reducing the thermal overheat issues for the machine prototype operation under fault-tolerant conditions.The research investigation presented in this thesis can be viewed as a comprehensive investigative analyses study on the design concept of the multi-threephase unit motor machine,its magnetic field distributions,radial force analysis,vibroacoustic behaviour,efficiency performance,and thermal consideration under normal and fault-tolerant conditions applying different three-phase sector winding designs for fault-tolerant applications.